Basic seedbox sharing questions

I have a couple of basic questions about sharing seedboxes.

1. With Windows and uTorrent webui, how many accounts/active torrents can I have with a Q6600 and 8GB RAM? Also, can I make accounts with the webui uTorrent?

2. Can it handle multiple harddrives without issues? If I was for instance putting external HDs on it, would it be able to use those fine? How would that work?

3. How does bandwidth delegate itself when over demanded by users? For instance, if I had 10 people sharing a 1GBit line, and each person wanted to use 200Mbits at an instance, would each user get 100Mbits, or would one get 200Mbits, another 175Mbits, another 125Mbits, and that takes away from everyone else? How does that work?